Maryland Department of Transportation State Highway Administration

Red-light cameras (RLC) are a popular countermeasure to reduce red-light running and improve intersection safety. Studies show that the reduction in side impact crashes at RLC intersections are often accompanied by no-change or an increase in the number of rear-end collisions. Part I of the study used crash data to evaluate twenty-seven RLC locations in Maryland. Part II conducted behavior observations at eight intersections to investigate if RLC impacts driver behavior, especially their responses to a yellow light. The eight intersections, two three-intersection clusters and two individual intersections, are in Montgomery and Prince George’s counties of Maryland. An intersection cluster includes a RLC intersection, and an upstream and a downstream non-RLC intersections for control comparisons. Findings indicate that a properly deployed RLC system can lead to the following impacts: (1) a reduction in side impact crashes; (2) changes in rear-end collisions depending on the local driving populations, (3) a reduction in aggressive driving behavior at the RLC and its downstream intersections; (4) more drivers reduce speeds when passing through a yellow phase, (5) more drivers choose to stop when encountering a yellow phase; and (6) less red-light-running vehicles.